The relatively large number of "credible" agents (chemical, radiological, and microbial contaminants) poses a special challenge for utilities,
emergency responders, health agencies, and government regulatory agencies that may be
required to respond to a bioterrorism threat (i.e., how to quickly analyze for a wide variety of
contaminants). Unfortunately, with the amount of time required to ship samples to reference laboratories
and conduct standard analyses on water containing unknown agents, it is anticipated that
significant public health responses and utility operational responses would be required prior to
the receipt of definitive analytical results. Rapid screening techniques that could yield even
"presumptive" results in a short amount of time, could provide important additional information
to decision makers managing the response to threatened or suspected incidents. These
techniques could include rapid immunoassays, rapid polymerase chain reaction screening, and
acute toxicity tests that could be conducted either in the field at the suspected sites of
contamination, or in a nearby utility, public health, commercial or regulatory agency laboratory.
Obviously, rapid screening techniques do not provide the same accuracy, precision, or
ability to definitively identify a contaminant, as do standard laboratory procedures. However, they offer the
advantage of rapid, presumptive results in an emergency situation. It is necessary to carefully
evaluate these rapid analytical techniques to determine their capabilities and limitations, as well
as their accuracy and precision. The purpose of the current study is to help determine these
characteristics for two of the commercially available acute toxicity screening devices, Microtox
and Eclox. The Microtox system is a broad-spectrum acute toxicity bioassay that can be used in the
laboratory or the field. Microtox is the lab version and Delatox is the portable field version.
Microtox (and Delatox) are based on a bacterial bioluminescence test described in method 8050
of Standard Methods (1998). The assay is a metabolic inhibition test that utilizes a suspension of
luminescent bacteria as a test organism. The test provides a rapid means for detecting the
presence of toxic substances. The Eclox system is a simple-to-use water assay that was developed as a field testing
kit for the British military. The original application was to enable soldiers to perform rapid tests
on raw water to determine treatability in the field and subsequently on treated water to determine
safety for consumption. However, the simplicity and speed of testing also make the kit attractive
for emergency use by water utilities concerned with the threat of intentional contamination.
The Eclox screen is a rapid chemiluminescence test for the presence of toxic substances.
The test utilizes a plant enzyme which when mixed with other reagents produces light. Certain
pollutants when present in water interfere with the chemical reaction and reduce the amount of
luminescence. The extent of inhibition of chemiluminescence is assumed to be proportional to
the concentration of the contaminant. An effective rapid screening method would have the following characteristics:
multiple toxins detectable;
can test for contaminants of concern;
appropriate detection levels (e.g., lower than public heath concerns);
test is quantitative;
test is reproducible;
false positive and negative results are minimal;
minimal time required to perform test;
minimal analytical skill required to perform test; and,
minimal cost for test equipment and supplies. The paper lists the sets of analyses that were performed to evaluate the effectiveness of the two screening methods. Includes 3 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 420 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 19 |
| Published : | 11/02/2003 |
